A small particle of semi digested food that when coughing or clearing the throat comes whizzing up into the moutht & when crushed has the distinctive odour of poo!
Jamie coughed up a whizzpoo ground it between his teeth & gave himself shitbreath
Same as "Whizpop" referring to the BFG series and Roald Dahl books in which the word is used to refer to breaking wind . Whizzpop is a spelling used in the BFG books and newspaper cartoon strips.
BFGdrank a bottle of Frobscottle and soon after there was a mighty whizzpop!